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A maths problem

Discussion in 'The Lounge' started by Cadbury, Feb 26, 2007.

  1. Cadbury

    Cadbury WiiChat Member

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    Differentiate e^xy, I can't do it, can anybody help?


    ^ means to the power of
     
  2. MztikalAce

    MztikalAce exstatic Wii Fan

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    isnt that xye^xy. I think not too sure as i did the differentiation of the expontial like in november and i forgot it straight after the A2 level maths exam in january lol. errr actually i just thought about it and i think you use chain rule i think lol.so differentiate the xy then times that by the differentiation of e^xy which is xye^xy, im not too sure though sorry
     
    #2 MztikalAce, Feb 26, 2007
    Last edited: Feb 26, 2007
  3. Cadbury

    Cadbury WiiChat Member

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    No it's not. You've got to differentiate with respect to x by the way.

    It's not differentiating e, differentiating with respect to x.
     
    #3 Cadbury, Feb 26, 2007
    Last edited: Feb 26, 2007
  4. MztikalAce

    MztikalAce exstatic Wii Fan

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    XD sorry then i cant help you :(, btw are you doing A levels?
     
  5. Cadbury

    Cadbury WiiChat Member

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    Yes I am.
     
  6. MztikalAce

    MztikalAce exstatic Wii Fan

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    ahhhhh cool what did you get for AS maths, i bet its better then mine lol
     
  7. Napalmbrain

    Napalmbrain WiiChat Member

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    The answer is ye^(xy). You have to use the chain rule:

    First, differentiate the "argument" of the function (in this case, xy) to give y. Then, differentiate the function itself, leaving the argument the same (and as you should know, the derivative of an exponential is still an exponential). Multiply the two answers to give ye^(xy).
     
  8. Cadbury

    Cadbury WiiChat Member

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    I got an E at AS level, but am getting A's and B's at A2, mad world eh?

    Thanks Napalmbrain, I'll look into it.
     
  9. lolz

    lolz based on a true story

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    math sucks. you'll never need to know half the **** they teach you.
     
  10. FR.

    FR. Moderator
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    I'm sure you'll be very surprised when you are an adult.
     
  11. kissoff182

    kissoff182 Comp Sci's Smurfette

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    damn, what level of calc are you in? Or is it just a diff. equations class?

    I was about to say it's the same as e^x * e^y, but then I was like, wait, that's e^(x+y), haha. I'm in calc 3 right now. =)

    All I can think of, which I'm sure you've already thought of, is to use (e^x)^y and go from there. Go where? I'm not sure.
     
  12. Sovieto

    Sovieto Banned

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    no he wont, even my math teacher says she barely uses half the stuff we learn, and its the easier more basic stuff, we learn all this **** because its better for getting into colleges, which leads into your life, if we all had to only go up to Algebra, then how would colleges decide who they want and who they dont? the more you can do proves how smart you are.

    get it?
     
  13. Axtlar

    Axtlar Del fuego he resurgido...

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    tsk tsk tsk Unitedstatians schools....
     
  14. The_Mitch

    The_Mitch UNACCEPTABLE

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    wow. i didnt even read the whole thread and got a headache! i HATE math so much lol. however i must leave now to go to night school for algebra 2 :(
     
  15. COLDshiver

    COLDshiver Wii Owner

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    Could use the chain rule with that?

    start with:
    y(e^x)^(y-1)(xe^(x-1))

    Dunno how to go from there...

    Hate natural logs :( :(
     
  16. Napalmbrain

    Napalmbrain WiiChat Member

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    Maths is useful, at least in some fields, e.g. engineering. Since I do physics I have to use calculus all the time, sometimes quite complicated equations. I hate those trigonometric ones, I can never remember the trigonometric identities you have to use.
     
  17. zeon9881

    zeon9881 Slowly drifting away

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    i ant wait till i go to high school and fininsh and go to uni and finish and then finally med school
     
  18. Cadbury

    Cadbury WiiChat Member

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    e^xy = 5

    xy = ln5

    y + x.dy/dx = 0

    dy/dx = -y/x

    There is your answer.
     
  19. Oceanic

    Oceanic The Cake is a Lie

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    you are trying to differentiate something with two variables, x and y. Therefore, you need to differentiate with respect to either x or y, not both (this is partial derivatives)
    So if you differentiate with respect to x, then your answer is ye^xy and if with respect to y, your answer will b e xe^xy, using the chain rule.
     
  20. jowii

    jowii Neurological Phenomenon

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    I'm in med school right now, and calc has definitely come in handy (which is prolly why its required).

    A lot of the pharmacokinetics stuff (drug doses, where it goes, and how long it takes to leave the body) uses a lot of calc. For instance any given drug, with a few exceptions, is eliminated from the body as an exponential decay function. The other really helpful part is just the way you learn to think about rates in calc. Even if you don't use the chain rule, etc, in everyday life, it helps you think about some problems in cool new ways.
     

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